The present invention generally relates to catalyst compositions useful for the polymerization or oligomerization of olefins, and to processes using the catalyst compositions. Certain of these catalyst compositions comprise a Group 8-10 metal complex comprising a bidentate or variable denticity ligand comprising one or two nitrogen donor atom or atoms independently substituted by an aromatic or heteroaromatic ring(s), wherein the ortho positions of said ring(s) are substituted by aryl or heteroaryl groups.
Olefin polymers are used in a wide variety of products, from sheathing for wire and cable to film. Olefin polymers are used, for instance, in injection or compression molding applications, in extruded films or sheeting, as extrusion coatings on paper, for example photographic paper and digital recording paper, and the like. Improvements in catalysts have made it possible to better control polymerization processes and, thus, influence the properties of the bulk material. Increasingly, efforts are being made to tune the physical properties of plastics for lightness, strength, resistance to corrosion, permeability, optical properties, and the like, for particular uses. Chain length, polymer branching and functionality have a significant impact on the physical properties of the polymer. Accordingly, novel catalysts are constantly being sought in attempts to obtain a catalytic process for polymerizing olefins which permits more efficient and better-controlled polymerization of olefins.
The use of late transition metal complexes as catalysts for olefin polymerization has recently been reviewed by Ittel et al. (Chem. Rev. 2000, 100, 1169). Notwithstanding the many advances described therein, there remains a need for new late transition metal catalysts and processes with improved productivities under the elevated temperatures and pressures of commercial reactor operating conditions. New catalysts and processes for these purposes are described herein.
In a first aspect, this invention relates to a catalyst composition useful for the polymerization of olefins, which comprises a Group 8-10 metal complex comprising a bidentate or variable denticity ligand comprising two nitrogen donor atoms independently substituted by aromatic or heteroaromatic rings, wherein the ortho positions of the rings are substituted by aryl or heteroaryl groups.
In a second aspect, this invention relates to a catalyst composition comprising either (i) a compound of formula ee1, (ii) the reaction product of a metal comples of formula ff1 and a second compound Y1, or (iii) the reaction product of Ni(1,5-cycloocatadiene)2, B(C6F5)3, a ligand selected from Set 18, and optionally an olefin;

wherein:
L2 is selected from Set 18;
T is H, hydrocarbyl, substituted hydrocarbyl, or other group capable of inserting an olefin;
L is an olefin or a neutral donor group capable of being displaced by an olefin; in addition, T and L may be taken together to form a xcfx80-allyl or xcfx80-benzyl group;
Xxe2x88x92 is BF4xe2x88x92, B(C6F5)4xe2x88x92, BPh4xe2x88x92, or another weakly coordinating anion;
Q and W1 are each independently fluoro, chloro, bromo or iodo, hydrocarbyl, substituted hydrocarbyl, heteroatom attached hydrocarbyl, heteroatom attached substituted hydrocarbyl, or collectively sulfate, or may be taken together to form a xcfx80-allyl, xcfx80-benzyl, or acac group, in which case a weakly coordinating counteranion Xxe2x88x92 is also present;
Y1 is either (i) a metal hydrocarbyl capable of abstracting acac from ff1 in exchange for alkyl or another group capable of inserting an olefin, (ii) a neutral Lewis acid capable of abstracting Q or W1 from ff1 to form a weakly coordinating anion, a cationic Lewis acid whose counterion is a weakly coordinating anion, or a Bronsted acid whose conjugate base is a weakly coordinating anion, or (iii) a Lewis acid capable of reacting with a xcfx80-allyl or it-benzyl group, or a substituent thereon, in ff1 to initiate olefin polymerization;
R3a,b are each independently H, alkyl, hydrocarbyl, substituted hydrocarbyl, 2,4,6-triphenylphenyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, or fluoroalkyl; and
Ar1a-d are each independently phenyl, 4-alkylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 4-hydroxyphenyl, 4-(heteroatom attached hydrocarbyl)-phenyl, 4-(heteroatom attached substituted hydrocarbyl)-phenyl, or 1-naphthyl.
In a first preferred embodiment of this second aspect, the metal complex of formula ff1 is selected from Set 19; 
wherein:
R3a,b are each independently H, methyl, phenyl, 4-methoxyphenyl, or 4-tert-butylphenyl;
Ar1a-d are each independently phenyl, 4-methylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 1-naphthyl, 2-naphthyl, or 4-phenylphenyl; and
Xxe2x88x92 is BF4xe2x88x92, B(C6F5)4xe2x88x92, BPh4xe2x88x92, or another weakly coordinating anion.
In a second preferred embodiment of this second aspect, the substituents Ar1a-d are 4-tert-butylphenyl or 1-naphthyl. In a third, especially preferred, embodiment, the catalyst composition further comprises a solid support.
In a third aspect, this invention relates to a process for the polymerization of olefins, comprising contacting one or more olefins with the catalyst composition of the second aspect. In a preferred embodiment, of this second aspect, the second compound Y1 is trimethylaluminum, and the metal complex is contacted with the trimethylaluminum in a gas phase olefin polymerization reactor.
In a fourth aspect, this invention relates to a compound of formula ii1; 
wherein:
R3a,b are each independently H, methyl, phenyl, 4-methoxyphenyl, or 4-tert-butylphenyl; and
Ar1a-d are each independently phenyl, 4-methylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 1-naphthyl, 2-naphthyl, or 4-phenylphenyl. Compounds of this formula are useful as ligands in constituting the catalysts of the present invention.
In a fifth aspect, the invention relates to a process for the polymerization of olefins, comprising contacting one or more olefins with a catalyst composition comprising a Group 8-10 transition metal complex which comprises a ligand selected from Set 20; 
wherein:
R2x,y are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, R2x and R2y may be linked by a bridging group;
R3a-f are each independently H, alkyl, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, or fluoroalkyl; and
Ar1a-d are each independently phenyl, 4-alkylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 4-hydroxyphenyl, 4-(heteroatom attached hydrocarbyl)-phenyl, 4-(heteroatom attached substituted hydrocarbyl)-phenyl, 1-naphthyl, 2-naphthyl, 9-anthracenyl, or aryl.
In a sixth aspect, this invention relates to a compound selected from Set 21; 
wherein:
R2x,y are each independently H, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, or heteroatom connected substituted hydrocarbyl; in addition, R2x and R2y may be linked by a bridging group;
R3a-f are each independently H, alkyl, hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, or fluoroalkyl; and
Ar1a-d are each independently phenyl, 4-alkylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 4-hydroxyphenyl, 4-(heteroatom attached hydrocarbyl)-phenyl, 4-(heteroatom attached substituted hydrocarbyl)-phenyl, 1-naphthyl, 2-naphthyl, 9-anthracenyl, or aryl. These compounds are are useful as ligands in constituting the catalysts of the present invention.
In a seventh aspect, this invention relates to a catalyst composition useful for the polymerization of olefins, which comprises a Group 8-10 transition metal complex comprising a N,N-donor ligand of the formula kk1 or kk2; 
wherein:
Ar2a,b are each independently aromatic or heteroaromatic groups wherein the ortho positions are substituted by aryl or heteroaryl groups;
M1 is a metal selected from Groups 3, 4, 5, 6, 13, or 14, or is Cu, P or As; and
Ln are ancillary ligands or groups which satisfy the valency of M1, such that M1 is either a neutral, monoanionic or cationic metal center, or is a neutral or cationic P or As, with suitable counterions such that said catalyst composition has no net charge. M1Ln may also be an active site for olefin polymerization. The compounds of formula kk2 are capable of ligating to two Group 8-10 metal centers, which may be the same or different, where one or both of said Group 8-10 metal centers may be active sites for olefin polymerization.
In an eighth aspect, this invention relates to a process for the polymerization of olefins, comprising contacting one or more olefins with the catalyst composition the seventh aspect.
We have surprisingly found that the catalyst compositions of the present invention can provide improved stability in the presence of an amount of hydrogen effective to achieve chain transfer, a total productivity greater than about 28,000 kg polyethylene per mole of catalyst at an operating temperature of at least 60xc2x0 C. (preferably greater than 56,000 kg PE/mol catalyst), and/or a higher productivity in the presence of an amount of hydrogen effective to achieve chain transfer, relative to the productivity observed in the absence of hydrogen.
In this disclosure, symbols ordinarily used to denote elements in the Periodic Table and commonly abbreviated groups, take their ordinary meaning, unless otherwise specified. Thus, N, O, S, P, and Si stand for nitrogen, oxygen, sulfur, phosphorus, and silicon, respectively, while Me, Et, Pr, iPr, Bu, tBu and Ph stand for methyl, ethyl, propyl, iso-propyl, butyl, tert-butyl and phenyl, respectively.
A xe2x80x9chydrocarbylxe2x80x9d group means a monovalent or divalent, linear, branched or cyclic group which contains only carbon and hydrogen atoms. Examples of monovalent hydrocarbyls include the following: C1-C20 alkyl; C1-C20 alkyl substituted with one or more groups selected from C1-C20 alkyl, C3-C8 cycloalkyl, and aryl; C3-C8 cycloalkyl; C3-C8 cycloalkyl substituted with one or more groups selected from C1-C20 alkyl, C3-C8 cycloalkyl, and aryl; C6-C14 aryl; and C6-C14 aryl substituted with one or more groups selected from C1-C20 alkyl, C3-C8 cycloalkyl, and aryl. Examples of divalent (bridging) hydrocarbyls include: xe2x80x94CH2xe2x80x94, xe2x80x94CH2CH2xe2x80x94, xe2x80x94CH2CH2CH2xe2x80x94, and 1,2-phenylene.
The term xe2x80x9carylxe2x80x9d refers to an aromatic carbocyclic monoradical, which may be substituted or unsubstituted, wherein the substituents are halo, hydrocarbyl, substituted hydrocarbyl, heteroatom attached hydrocarbyl, heteroatom attached substituted hydrocarbyl, nitro, cyano, fluoroalkyl, sulfonyl, and the like. Examples include: phenyl, naphthyl, anthracenyl, phenanthracenyl, 2,6-diphenylphenyl, 3,5-dimethylphenyl, 4-nitrophenyl, 3-nitrophenyl, 4-methoxyphenyl, 4-dimethylaminophenyl, and the like.
A xe2x80x9cheterocyclic ringxe2x80x9d refers to a carbocyclic ring wherein one or more of the carbon atoms has been replaced by an atom selected from the group consisting of O, N, S, P, Se, As, Si, B, and the like.
A xe2x80x9cheteroaromatic ringxe2x80x9d refers to an aromatic heterocycle; examples include pyrrole, furan, thiophene, indene, imidazole, oxazole, isoxazole, carbazole, thiazole, pyrimidine, pyridine, pyridazine, pyrazine, benzothiophene, and the like.
A xe2x80x9cheteroarylxe2x80x9d refers to a heterocyclic monoradical which is aromatic; examples include 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl, furyl, thienyl, indenyl, imidazolyl, oxazolyl, isoxazolyl, carbazolyl, thiazolyl, pyrimidinyl, pyridyl, pyridazinyl, pyrazinyl, benzothienyl, and the like, and substituted derivatives thereof.
A xe2x80x9csilylxe2x80x9d group refers to a SiR3 group wherein Si is silicon and R is hydrocarbyl or substituted hydrocarbyl or silyl, as in Si(SiR3)3.
A xe2x80x9cborylxe2x80x9d group refers to a BR2 or B(OR)2 group, wherein R is hydrocarbyl or substituted hydrocarbyl.
A xe2x80x9cheteroatomxe2x80x9d refers to an atom other than carbon or hydrogen. Preferred heteroatoms include oxygen, nitrogen, phosphorus, sulfur, selenium, arsenic, chlorine, bromine, silicon, and fluorine.
A xe2x80x9csubstituted hydrocarbylxe2x80x9d refers to a monovalent, divalent, or trivalent hydrocarbyl substituted with one or more heteroatoms. Examples of monovalent substituted hydrocarbyls include: 2,6-dimethyl-4-methoxyphenyl, 2,6-diisopropyl-4-methoxyphenyl, 4-cyano-2,6-dimethylphenyl, 2,6-dimethyl-4-nitrophenyl, 2,6-difluorophenyl, 2,6-dibromophenyl, 2,6-dichlorophenyl, 4-methoxycarbonyl-2,6-dimethylphenyl, 2-tert-butyl-6-chlorophenyl, 2,6-dimethyl-4-phenylsulfonylphenyl, 2,6-dimethyl-4-trifluoromethylphenyl, 2,6-dimethyl-4-trimethylammoniumphenyl (associated with a weakly coordinated anion), 2,6-dimethyl-4-hydroxyphenyl, 9-hydroxyanthr-10-yl, 2-chloronapth-1-yl, 4-methoxyphenyl, 4-nitrophenyl, 9-nitroanthr-10-yl, xe2x80x94CH2OCH3, cyano, trifluoromethyl, and fluoroalkyl. Examples of divalent (bridging) substituted hydrocarbyls include: 4-methoxy-1,2-phenylene, 1-methoxymethyl-1,2-ethanediyl, 1,2-bis(benzyloxymethyl)-1,2-ethanediyl, and 1-(4-methoxyphenyl)-1,2-ethanediyl. Examples of trivalent hydrocarbyls include methine and phenyl-substituted methane.
A xe2x80x9cheteroatom connected hydrocarbylxe2x80x9d refers to a group of the type E10(hydrocarbyl), E20H(hydrocarbyl), or E20(hydrocarbyl)2, where E10 is an atom selected from Group 16 and E20 is an atom selected from Group 15.
A xe2x80x9cheteroatom connected substituted hydrocarbylxe2x80x9d refers to a group of the type E10(substituted hydrocarbyl), E20H(substituted hydrocarbyl), or E20(substituted hydrocarbyl)2, where E10 is an atom selected from Group 16 and E20 is an atom selected from Group 15.
The term xe2x80x9cfluoroalkylxe2x80x9d as used herein refers to a C1-C20 alkyl group substituted by one or more fluorine atoms.
An xe2x80x9colefinxe2x80x9d refers to a compound of the formula R1aCHxe2x95x90CHR1b, where R1a and R1b may independently be H, hydrocarbyl, substituted hydrocarbyl, fluoroalkyl, silyl, O(hydrocarbyl), or O(substituted hydrocarbyl), and where R1a and R1b may be connected to form a cyclic olefin, provided that in all cases, the substituents R1a and R1b are compatible with the catalyst. In the case of most Group 4-7 catalysts, this will generally mean that the olefin should not contain good Lewis base donors, since this will tend to severely inhibit catalysis. Preferred olefins for such catalysts include ethylene, propylene, butene, hexene, octene, cyclopentene, norbornene, and styrene.
In the case of the Group 8-10 catalysts, Lewis basic substituents on the olefin will tend to reduce the rate of catalysis in most cases; however, useful rates of homopolymerization or copolymerization can nonetheless be achieved with some of those olefins. Preferred olefins for such catalysts include ethylene, propylene, butene, hexene, octene, and fluoroalkyl substituted olefins, but may also include, in the case of palladium and some of the more functional group tolerant nickel catalysts, norbornene, substituted norbornenes (e.g., norbornenes substituted at the 5-position with halide, siloxy, silane, halo carbon, ester, acetyl, alcohol, or amino groups), cyclopentene, ethyl undecenoate, acrylates, vinyl ethylene carbonate, 4-vinyl-2,2-dimethyl-1,3-dioxolane, and vinyl acetate.
In some cases, the Group 8-10 catalysts can be inhibited by olefins which contain additional olefinic or acetylenic functionality. This is especially likely if the catalyst is prone to xe2x80x9cchain-runningxe2x80x9d wherein the catalyst can migrate up and down the polymer chain between insertions, since this can lead to the formation of relatively unreactive xcfx80-allylic intermediates when the olefin monomer contains additional unsaturation. Such effects are best determined on a case-by-case basis, but may be predicted to some extent through knowledge of how much branching is observed with a given catalyst in ethylene homopolymerizations; those catalysts which tend to give relatively high levels of branching with ethylene will tend to exhibit lower rates when short chain diene co-monomers are used under the same conditions. Longer chain dienes tend to be less inhibitory than shorter chain dienes, when other factors are kept constant, since the catalyst has farther to migrate to form the xcfx80-allyl, and another insertion may intervene first.
Similar considerations apply to unsaturated esters which are capable of inserting and chain-running to form relatively stable intramolecular chelate structures wherein the Lewis basic ester functionality occupies a coordination site on the catalyst. In such cases, short chain unsaturated esters, such as methyl acrylate, tend to be more inhibitory than long chain esters, such as ethyl undecenoate, if all other factors are kept constant.
A xe2x80x9cxcfx80-allylxe2x80x9d group refers to a monoanionic group with three sp2 carbon atoms bound to a metal center in a xcex73-fashion. Any of the three sp2 carbon atoms may be substituted with a hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, or O-silyl group. Examples of xcfx80-allyl groups include: 
The term xcfx80-benzyl group denotes an xcfx80-allyl group where two of the sp2 carbon atoms are part of an aromatic ring. Examples of xcfx80-benzyl groups include: 
A xe2x80x9cbridging groupxe2x80x9d refers to an atom or group which links two or more groups, which has an appropriate valency to satisfy its requirements as a bridging group, and which is compatible with the desired catalysis. Suitable examples include divalent or trivalent hydrocarbyl, substituted hydrocarbyl, heteroatom connected hydrocarbyl, heteroatom connected substituted hydrocarbyl, substituted silicon(IV), boron(III), N(III), P(III), and P(V), xe2x80x94C(O)xe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94C(S)xe2x80x94, xe2x80x94B(OMe)xe2x80x94, xe2x80x94C(O)C(O)xe2x80x94, O, S, and Se. In some cases, the groups which are said to be xe2x80x9clinked by a bridging groupxe2x80x9d are directly bonded to one another, in which case the term xe2x80x9cbridging groupxe2x80x9d is meant to refer to that bond. By xe2x80x9ccompatible with the desired catalysis,xe2x80x9d we mean a bridging group or substituent which either does not interfere with the desired catalysis, or acts to usefully modify the catalyst activity or selectivity.
The term xe2x80x9cweakly coordinating anionxe2x80x9d is well known in the art per se and generally refers to a large bulky anion capable of delocalization of the negative charge of the anion. Weakly coordinating anions, not all of which would be considered bulky, include, but are not limited to: B(C6F5)4xe2x88x92, PF6xe2x88x92, BF4xe2x88x92, SbF6xe2x88x92, (F3CSO2)2Nxe2x88x92, (F3CSO2)3Cxe2x88x92, (Ph)4Bxe2x88x92 wherein Ph=phenyl, and Ar4Bxe2x88x92 wherein Ar4Bxe2x88x92=tetrakis[3,5-bis(trifluoromethyl)phenyl]-borate. The weakly coordinating nature of such anions is known and described in the literature (S. Strauss et al., Chem. Rev., 1993, 93, 927).
The term xe2x80x9corthoxe2x80x9d is used herein in the context of the ligands of the present invention to denote the positions which are adjacent to the point of attachment of the aromatic or heteroaromatic ring to the ligated nitrogen(s). In the case of a 1-attached, 6-membered ring, we mean the 2- and 6-positions. In the case of a 1-attached, 5-membered ring, we mean the 2- and 5-positions. In the case of 1-attached, fused ring aromatic or heteroaromatic rings, we mean the first positions which can be substituted; for example, in the case of 1-naphthyl, these would be the 2- and 8-positions; in the case of 9-anthracenyl, these would be the 1- and 8-positions.
The term xe2x80x9cvariable denticityxe2x80x9d is used herein in the context of otherwise bidentate ligands to refer to the reversible formation of a third binding interaction between the ligand and the Group 8-10 transition metal center to which it is complexed.
The abbreviation xe2x80x9cacacxe2x80x9d refers to acetylacetonate. In general, substituted acetylacetonates, wherein one or more hydrogens in the parent structure have been replaced by a hydrocarbyl, substituted hydrocarbyl, or fluoroalkyl, may be used in place of the xe2x80x9cacacxe2x80x9d. Hydrocarbyl substituted acetylacetonates may be preferred in some cases when it is important, for example, to improve the solubility of a (ligand)Ni(acac)BF4 salt in mineral spirits.
The phrase xe2x80x9can amount of hydrogen effective to achieve chain transferxe2x80x9d refers to the ability of hydrogen to react with an olefin polymerization catalyst to cleave off a growing polymer chain and initiate a new chain. In most cases, this is believed to involve hydrogenolysis of the metal-carbon bond of the growing polymer chain, to form a metal hydride catalytic intermediate, which can then react with the olefin monomer to initiate a new chain. In the context of the current invention, an effective amount is considered to be that amount of hydrogen which reduces both the number average molecular weight and the weight average molecular weight of the polymer by at least 10%, relative to an otherwise similar reaction conducted in the absence of hydrogen. In this context, xe2x80x9cotherwise similarxe2x80x9d denotes that the catalyst, catalyst loading, solvent, solvent volume, agitation, ethylene pressure, co-monomer concentration, reaction time, and other process relevant parameters are sufficiently similar that a valid comparison can be made.
In general, previously reported catalysts lacking the novel ortho-aryl substitution pattern of the current invention are far less productive in the presence of an amount of hydrogen effective to achieve chain transfer than they are under otherwise similar conditions without hydrogen. In order to quantify this effect, the following terms are defined.
The productivity P is defined as the grams of polymer produced per mole of catalyst, over a given period of time. The productivity Phydrogen is defined as the grams of polymer produced per mole of catalyst in the presence of an amount of hydrogen effective to achieve chain transfer, in an otherwise similar reaction conducted for the same period of time. Catalysts lacking the novel ortho-aryl substitution pattern of the catalyst compositions of the current invention typically exhibit ratios Phydrogen/P less than or equal to 0.05 under substantially non-mass transport limited conditions.
The phrase xe2x80x9cimproved stability in the presence of an amount of hydrogen effective to achieve chain transferxe2x80x9d means that the ratio Phydrogen/P is at least 0.1 under substantially non-mass transport limited conditions. Preferred catalysts of the present invention exhibit a ratio Phydrogen/P greater than or equal to 0.2 under substantially non-mass transport limited conditions. Especially preferred catalysts of the present invention exhibit a ratio Phydrogen/P greater than or equal to 0.5 under substantially non-mass transport limited conditions.
The phrase xe2x80x9cone or more olefinsxe2x80x9d refers to the use of one or more chemically different olefin monomer feedstocks, for example, ethylene and propylene.
The phrase xe2x80x9ccapable of inserting an olefinxe2x80x9d refers to a group Z bonded to the transition metal M, which can insert an olefin monomer of the type R1aCHxe2x95x90CHR1b to form a moiety of the type Mxe2x80x94CHR1axe2x80x94CHR1bxe2x80x94Z, which can subsequently undergo further olefin insertion to form a polymer chain; wherein R1a and R1b may independently be H, hydrocarbyl, substituted hydrocarbyl, fluoroalkyl, silyl, O(hydrocarbyl), or O(substituted hydrocarbyl), and wherein R1a and R1b may be connected to form a cyclic olefin, provided that in all cases, the substituents R1a and R1b are compatible with the desired catalysis; wherein additional groups will be bound to the transition metal M to comprise the actual catalyst, as discussed in more detail below.
The degree of steric hindrance at the active catalyst site required to give slow chain transfer, and thus form polymer, depends on a number of factors and is often best determined by experimentation. These factors include: the exact structure of the catalyst, the monomer or monomers being polymerized, whether the catalyst is in solution or attached to a solid support, and the temperature and pressure. The term xe2x80x9cpolymerxe2x80x9d is defined herein as corresponding to a degree of polymerization, DP, of about 10 or more; oligomer is defined as corresponding to a DP of 2 to about 10.
The term xe2x80x9ctotal productivityxe2x80x9d is defined in the context of ethylene polymerization as the number of kilograms of polyethylene per mole of catalyst and is the maximum weight of polyethylene that can be produced using a given catalyst.
By xe2x80x9csuitable counterionsxe2x80x9d, we mean weakly coordinating ions with sufficient charge to give the overall catalyst complex no net charge.
In the context of structures kk1 and kk2, xe2x80x9cancillary ligandsxe2x80x9d are atoms or groups which serve to satisfy the valency of M1 without interfering with the desired catalysis.
The compounds of Sets 18-21 and formula ii1 may be prepared as described in the examples contained herein, or by methods described in the references cited by Ittel et al. (Chem. Rev. 2000, 100, 1169); or in U.S. patent application Ser. No. 09/507,492, filed on Feb. 18, 2000, Ser. No. 09/563,812, filed on May 3, 2000, and Ser. No. 09/231,920, filed on Sep. 11, 2000; or in U.S. Provisional Application Nos. 60/246,254, 60/246,255, and 60/246,178, all filed on Nov. 6, 2000.
A variety of protocols may be used to generate active polymerization catalysts comprising transition metal complexes of various nitrogen, phosphorous, oxygen and sulfur donor ligands. Examples include: (i) the reaction of a Ni(II), Pd(II), Co(II) or Fe(II) dihalide complex of a bidentate N,N-donor ligand with an alkylaluminum reagent, for example, the reaction of (bidentate N,N-donor ligand)Ni(acac)X salts with an alkylaluminum reagent, where X is a weakly coordinating anion, such as B(C6F5)4xe2x88x92, BF4xe2x88x92, PF6xe2x88x92, SbF6xe2x88x92 and OS(O)2CF3xe2x88x92, (ii) the reaction of a bidentate N,N-donor ligand with bis(1,5-cyclooctadiene)nickel(0) and [H(OEt2)2]+[B(3,5-(CF3)2C6H3)4]xe2x88x92, and (iii) the reaction of a bidentate N,N-donor ligand with bis(1,5-cyclooctadiene)nickel(0) and B(C6F5)3. Cationic [(ligand)M(xcfx80-allyl)]+ complexes with weakly coordinating counteranions, where M is a Group 10 transition metal, are often also suitable catalyst precursors, requiring only exposure to olefin monomer and in some cases elevated temperatures (40-100xc2x0 C.) or added Lewis acid, or both, to form an active polymerization catalyst.
More generally, a variety of (ligand)nM(Z1a)(Z1b) complexes, where xe2x80x9cligandxe2x80x9d refers to a compound of the present invention and is a bidentate or variable denticity ligand comprising one or two nitrogen donor atom or atoms independently substituted by an aromatic or heteroaromatic ring(s), wherein the ortho positions of the ring(s) are substituted by aryl or heteroaryl groups, n is 1 or 2, M is a Group 8-10 transition metal, and Z1a and Z1b are univalent groups, or may be taken together to form a divalent group, may be reacted with one or more compounds, collectively referred to as compound Y1, which function as co-catalysts or activators, to generate an active catalyst of the form [(ligand)nM(T1a)(L)]+Xxe2x88x92, where n is 1 or 2, T1a is a hydrogen atom or hydrocarbyl, L is an olefin or neutral donor group capable of being displaced by an olefin, M is a Group 8-10 transition metal, and Xxe2x88x92 is a weakly coordinating anion. When Z1a and Z1b are both halide, examples of compound Y1 include: methylaluminoxane (herein MAO) and other aluminum sesquioxides, R3Al, R2AlCl, and RAlCl2 (wherein R is alkyl, and plural groups R may be the same or different). When Z1a and Z1b are both alkyl, examples of a compound Y1 include: MAO and other aluminum sesquioxides, R3Al, R2AlCl, RAlCl2 (wherein R is alkyl, and plural groups R may be the same or different), B(C6F5)3, R03Sn[BF4] (wherein R0 is hydrocarbyl or substituted hydrocarbyl and plural groups R0 may be the same or different), H+Xxe2x88x92, wherein X is a weakly coordinating anion, for example, tetrakis[3,5-bis (trifluoromethyl)phenyl]borate, and Lewis acidic or Bronsted acidic metal oxides, for example, montmorillonite clay. In some cases, for example, when Z1a and Z1b are both halide or carboxylate, sequential treatment with a metal hydrocarbyl, followed by reaction with a Lewis acid, may be required to generate an active catalyst. Examples of metal hydrocarbyls include: MAO, other aluminum sesquioxides, R3Al, R2AlCl, RAlCl2 (wherein R is alkyl, and plural groups R may be the same or different), Grignard reagents, organolithium reagents, and diorganozinc reagents. Examples of Lewis acids include: MAO, other aluminum sesquioxides, R3Al, R2AlCl, RAlCl2 (wherein R is alkyl, and plural groups R may be the same or different), B(C6F5)3, R03Sn[BF4] (wherein R0 is hydrocarbyl or substituted hydrocarbyl and plural groups R0 may be the same or different), and Lewis acidic metal oxides.
The foregoing discussion is intended to illustrate that there are frequently many ways to generate an active catalyst. There are a variety of methods wherein the ligands of the present invention can be reacted with a suitable metal precursor, and optionally a co-catalyst, to generate an active olefin polymerization catalyst. Without wishing to be bound by theory, we believe that the active catalyst typically comprises the catalytically active metal, one or more ligands of the present invention, the growing polymer chain (or a hydride capable of initiating a new chain), and a site on the metal adjacent to the metal-alkyl bond of said chain where ethylene can coordinate, or at least closely approach, prior to insertion. Where specific structures for active catalysts have been implied herein, it should be understood that active catalysts comprising the ligands of the present invention are formed as the reaction products of the catalyst activation reactions disclosed herein, regardless of the detailed structures of those active species.
In some cases, it is advantageous to attach the catalyst to a solid support. Examples of useful solid supports include: inorganic oxides, such as talcs, silicas, titania, silica/chromia, silica/chromia/titania, silica/alumina, zirconia, aluminum phosphate gels, silanized silica, silica hydrogels, silica xerogels, silica aerogels, montmorillonite clay and silica co-gels, as well as organic support materials such as polystyrene and functionalized polystyrene. (See, for example, S. B. Roscoe et al., xe2x80x9cPolyolefin Spheres from Metallocenes Supported on Non-Interacting Polystyrene,xe2x80x9d 1998, Science, 280, 270-273 (1998)).
Thus, in a preferred embodiment, the catalysts of the present invention are attached to a solid support (by xe2x80x9cattached to a solid supportxe2x80x9d is meant ion paired with a component on the surface, adsorbed to the surface or covalently attached to the surface) that has been pre-treated with a compound Y1. More generally, the compound Y1 and the solid support can be combined in any order and any number of compound(s) Y1 can be utilized. In addition, the supported catalyst thus formed may be treated with additional quantities of compound Y1. In another preferred embodiment, the compounds of the present invention are attached to silica that has been pre-treated with an alkylaluminum compound Y1, for example, MAO, Et3Al, iBu3Al, Et2AlCl, or Me3Al.
Such supported catalysts are prepared by contacting the transition metal compound, in a substantially inert solvent (by which is meant a solvent which is either unreactive under the conditions of catalyst preparation, or if reactive, acts to usefully modify the catalyst activity or selectivity) with MAO-treated silica for a sufficient period of time to generate the supported catalyst. Examples of substantially inert solvents include toluene, o-difluorobenzene, mineral spirits, hexane, CH2Cl2, and CHCl3.
In another preferred embodiment, the catalysts of the present invention are activated in solution under an inert atmosphere, and then adsorbed onto a silica support which has been pre-treated with a silylating agent to replace surface silanols by trialkylsilyl groups. Methods to pre-treat silicas in this way are known to those skilled in the art and may be achieved, for example, by heating the silica with hexamethyldisilazane and then removing the volatiles under vacuum. A variety of precurors and procedures may be used to generate the activated catalyst prior to said adsorption, including, for example, reaction of a (ligand)Ni(acac)B(C6F5)4 complex with Et2AlCl in a toluene/hexane mixture under nitrogen; where xe2x80x9cligandxe2x80x9d refers to a compound of the present invention.
The polymerizations may be conducted in batch or continuous processes, as solution polymerizations, as non-solvent slurry type polymerizations, as slurry polymerizations using one or more of the olefins or other solvent as the polymerization medium, or in the gas phase. One of ordinary skill in the art, with the present disclosure, would understand that the catalyst could be supported using a suitable catalyst support and methods known in the art. Substantially inert solvents, such as toluene, hydrocarbons, methylene chloride and the like, may be used. Propylene and 1-butene are excellent monomers for use in slurry-type copolymerizations and unused monomer can be flashed off and reused.
Temperature and olefin pressure have significant effects on polymer structure, composition, and molecular weight. Suitable polymerization temperatures are preferably from about 20xc2x0 C. to about 160xc2x0 C., more preferably 60xc2x0 C. to about 100xc2x0 C. Suitable polymerization pressures range from about 1 bar to 200 bar, preferably 5 bar to 50 bar, and more preferably from 10 bar to 50 bar.
The catalyst concentration in solution, or loading on a support, is adjusted to give a level of activity suitable for the process and desired polymer. In the case of solution phase or a slurry phase process using a soluble catalyst precursor, suitable catalyst concentrations are typically in the range of 0.01 to 100 micromoles/L, preferably 0.1 to 10 micromoles/L, even more preferably 0.2 to 2 micromoles/L. Higher loadings tend to reduce the solution phase concentration of ethylene at a given temperature, pressure and agitation rate, and can therefore result in relatively more chain running and branching in some cases.
In some cases, it is possible that the catalysts of the present invention may acquire new hydrocarbyl substituents, attached to the ligand or counteranion, or both, under the conditions of the olefin polymerization reaction. For example, if a bidentate N,N-donor ligand of the current invention underwent cyclometallation to form a tridentate ligand with a nickel-carbon bond, insertion of one or more ethylenes into this bond, followed by hydrogenolysis or by xcex2-H elimnation, could result in a new hydrocarbyl side chain attached to said ligand. Alternatively, the ligand could comprise an olefinic side chain substituent prior to polymerization, and this side chain could undergo copolymerization in the presence of ethylene to attach an oligomeric or polymeric group to the ligand. It is also possible that the reaction product of (i) bis(1,5-cyclooctadiene)nickel(0), (ii) a ligand of the present invention and (iii) B(C6F5)3 may comprise a cycloctadiene-derived hydrocarbyl bridge between cationic nickel and anionic boron, and subsequent ethylene insertion may result in the attachment of a polyethylene chain to the borate counteranion. Therefore, although hydrocarbyl groups attached to the ligand or counteranion of the current invention will generally be relatively low molecular weight groups (less than about MW=500), it is possible that they will be modified as described above under some olefin polymerization reaction conditions, and any such modified catalysts are also considered within the scope of this invention.
The catalysts of the present invention may be used alone, or in combination with one or more other Group 3-10 olefin polymerization or oligomerization catalysts, in solution, slurry, or gas phase processes. Such mixed catalysts systems are sometimes useful for the production of bimodal or multimodal molecular weight or compositional distributions, which may facilitate polymer processing or final product properties.
After the reaction has proceeded for a time sufficient to produce the desired polymers, the polymer can be recovered from the reaction mixture by routine methods of isolation and/or purification.
In general, the polymers of the present invention are useful as components of thermoset materials, as elastomers, as packaging materials, films, compatibilizing agents for polyesters and polyolefins, as a component of tackifying compositions, and as a component of adhesive materials.
High molecular weight resins are readily processed using conventional extrusion, injection molding, compression molding, and vacuum forming techniques well known in the art. Useful articles made from them include films, fibers, bottles and other containers, sheeting, molded objects and the like.
Low molecular weight resins are useful, for example, as synthetic waxes and they may be used in various wax coatings or in emulsion form. They are also particularly useful in blends with ethylene/vinyl acetate or ethylene/methyl acrylate-type copolymers in paper coating or in adhesive applications.
Although not required, typical additives used in olefin or vinyl polymers may be used in the new homopolymers and copolymers of this invention. Typical additives include pigments, colorants, titanium dioxide, carbon black, antioxidants, stabilizers, slip agents, flame retarding agents, and the like. These additives and their use in polymer systems are known per se in the art.
Other features of the invention will become apparent in the following description of working examples, which have been provided for illustration of the invention and are not intended to be limiting thereof.
The molecular weight data presented in the following examples is determined at 135xc2x0 C. in 1,2,4-trichlorobenzene using refractive index detection, calibrated using narrow molecular weight distribution poly(styrene) standards.